i already have one of these, but its starting to die, so i decided to make my own.
Step 1: case
i needed something cylindrical and after experimenting around i decided on 3 basic criteria:
1 again, it had to be cylindrical.
2 it had to be re-close able.
3 it had to be lying around the house somewhere.
a film canister was close but just a little bit too small, and i finally decided on an empty pill bottle.